The study assessed the extent that Philadelphia’s smoking ordinance diffused to Chinatown businesses and identified attitudinal and other barriers to implementation. Guided by constructs from Diffusion of Innovations and Theory of Planned Behavior, a cross-sectional study was conducted. The majority of business owners and employees lacked in-depth knowledge of relevant details of the policy, suggesting that the extent of its diffusion was limited. Retail businesses were more likely to witness smoking post-enactment than restaurants and had more difficulty with implementation. A multi-faceted diffusion strategy through communication channels familiar to the Chinatown community is needed to improve implementation and compliance.